Manufacture of open containers



April 1938- E. ENGLISCHET AL 2,113,373

MANUFACTURE OF OPEN CONTAINERS Filed Jan. 26, 1935 INVENTORS ATTORNEY Patented Apr. 5, 1938 UNITED STATES PATENT OFFICE MANUFACTURE OF OPEN CONTAINERS Ernst Englisch,

Steyr, and Hubert Richter,

Steyr, Austria Application January 26, 1935, Serial No. 3,548 In Austria. February 10, 1934 2 Claims.

This invention relates to open containers and their manufacture.

In drawing for instance containers, more particularly bath tubs, from a piece of sheet metal is adapted to be drawn various difiiculties are encountered. Owing to the size of the work and the necessity of dividing up the drawing operation into several successive operations, the hitherto usual method, in which the sheet or work had to be preheated once or several times, had certain known disadvantages and was relatively very costly. On the other hand attempts to carry out these operations without heating or intermediate heating of the sheet or work, that is in the cold state, led to no useful results. Experience has shown that with this method it is not possible to avoid the sheet becoming torn and folds forming in it, or that the flat, oppositely disposed longer sides of the finished bath become undulating and have to be straightened by a costly beating out by hand. There are further disadvantages for the enamelling process which usually follows, in that the fiat side walls are apt to warp through the necessary heating, which not only detrimentally affects their good appearance, but also the durability of the enamel, which easily cracks and springs off. When such bath tubs with warped side walls are in use, these side walls may, on the bath being filled with water, snap over in the other direction, which is unsightly, unpleasant, noisy and bad for the enamel. These disadvantages are avoided by a method of manufacture according to the invention. The invention consists in a method of manufacturing open containers having oppositely disposed longer side walls, more particularly bath tubs which are to be enamelled, by drawing from a single piece of sheet metal. The method consists in this, that these side walls are drawn so as to be slightly bulged outwards (convex or barrelled), which enables the process to be carried out in the cold state, more particularly, when this barrelling is effected in two directions at right angles to one another. The accompanying drawing shows an example of how this method is carried out in practice,

Fig. 1 representing a bath tub according to the invention in plan view and Fig. 2 in cross-section taken across the center of Fig. 1,

Fig. 3 shows means for fixing a foot in crosssection to an enlarged scale and Fig. 4 the same in plan view. It has been found by experiments, that through giving the drawing tools for the bath tub a suitable shape the oppositely disposed longer side walls I, 2, which have hitherto been made flat, can be given a slightly outwardly barrelled form, such as that indicated by the deviation 3 from the straight longitudinal line 4-4 in the plan view (Fig. 1) and from the straight vertical line 55 in the cross-section (Fig. 2), that is to say, that the barrelling is in two directions at right angles to one another.

Through the side walls I, 2 being given such a shape, not only is an excessive forming of folds in the sheet, more particularly in the vicinity of the rounded corners 6 (Figs. 1 and 2) completely avoided, but the stressing of the material during the drawing operation is caused to be so uniform that there will no longer be any tearing of the sheet, more particularly at the end walls of the bath tub (say at the line I, Fig. 2). In addition, through this slight outward barrelling of the side walls, the finished bath tub has a considerably increased rigidity imparted to it, which is of considerable importance for the usual subsequent enamelling operation and for the durability of the enamel and also greatly enhances the appearance and other properties of the finished bath.

The fiat metal sheet or stock is clamped between a pair of templets having centrally aligned openings. A drawing block having side walls bulging out longitudinally and vertically draws the middle part of the sheet to shape the bottom form and the lower portions of the side wall of the tub. After this drawing step, the partially formed tub is removed from the templets and placed between another pair of templets having larger openings and the drawing block again operates building up the side wall higher, the bottom remaining unchanged.

The partially formed tub is removed from the latter templets and placed between. different templets having larger openings and the drawing block is again brought into operation and the side wall is further built up and so on until finally finished.

In all of the drawing steps, the same drawing block is used, the external shape of which is throughout that of the finished hollow form of the tub, with the exception of the rolled edge. After the completion of the drawing operation the marginal roll 8 or if required a flat rim, is formed by pressing and the rim trimmed by cutting.

For fixing the feet, pieces of sheet metal 9 (Figs. 3 and 4) formed by being pressed out of their plane and cut out to a U-shape are electrically welded to the bottom of the bath tub, before the finished drawn and pressed bath tub is enamelled. Into these pieces of sheet metal the heads of the feet are inserted, being fixed by means of screws. Only a small amount of local heating of the bath tub is thus necessary, so that the strength of the cold drawn sheet is not reduced.

Specially good quality containers or bath tubs, which are of good appearance, rigid and durable can be made according to the invention with the minimum expenditure of material.

What we claim is:-

l. The method of manufacturing a bath tub having two oppositely disposed side walls longer than the end walls consisting of drawing said tub out of sheet metal and during at least a portion of said drawing operation shaping at least the long side walls to have a double curvature bulged outwards in both longitudinal and vertical directions, whereby these sides are more rigid and less liable to snap or buckle than is a substantially flat longitudinal side of similar material and whereby any subsequently applied enamel is in less danger of being cracked.

2. The method of forming a one piece sheet metal receptacle of elongated form like a bath tub which comprises drawing a generally rectangular portion of the sheet metal from its general plane and gradually laterally bulging each side of the rectangular part outward substantially simultaneously with the formation of a depression, at least the elongated sides being curved outward in both longitudinal and vertical directions whereby the metal is stressed more nearly uniformly and the tendency to form folds or corrugations in the sides is substantially reduced.

ERNST ENGLISCH. HUBER-T RICHTER. 

